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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * <linux/swait.h> (simple wait queues ) implementation:
4 */
5
6void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
7 struct lock_class_key *key)
8{
9 raw_spin_lock_init(&q->lock);
10 lockdep_set_class_and_name(&q->lock, key, name);
11 INIT_LIST_HEAD(&q->task_list);
12}
13EXPORT_SYMBOL(__init_swait_queue_head);
14
15/*
16 * The thing about the wake_up_state() return value; I think we can ignore it.
17 *
18 * If for some reason it would return 0, that means the previously waiting
19 * task is already running, so it will observe condition true (or has already).
20 */
21void swake_up_locked(struct swait_queue_head *q)
22{
23 struct swait_queue *curr;
24
25 if (list_empty(&q->task_list))
26 return;
27
28 curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
29 wake_up_process(curr->task);
30 list_del_init(&curr->task_list);
31}
32EXPORT_SYMBOL(swake_up_locked);
33
34/*
35 * Wake up all waiters. This is an interface which is solely exposed for
36 * completions and not for general usage.
37 *
38 * It is intentionally different from swake_up_all() to allow usage from
39 * hard interrupt context and interrupt disabled regions.
40 */
41void swake_up_all_locked(struct swait_queue_head *q)
42{
43 while (!list_empty(&q->task_list))
44 swake_up_locked(q);
45}
46
47void swake_up_one(struct swait_queue_head *q)
48{
49 unsigned long flags;
50
51 raw_spin_lock_irqsave(&q->lock, flags);
52 swake_up_locked(q);
53 raw_spin_unlock_irqrestore(&q->lock, flags);
54}
55EXPORT_SYMBOL(swake_up_one);
56
57/*
58 * Does not allow usage from IRQ disabled, since we must be able to
59 * release IRQs to guarantee bounded hold time.
60 */
61void swake_up_all(struct swait_queue_head *q)
62{
63 struct swait_queue *curr;
64 LIST_HEAD(tmp);
65
66 raw_spin_lock_irq(&q->lock);
67 list_splice_init(&q->task_list, &tmp);
68 while (!list_empty(&tmp)) {
69 curr = list_first_entry(&tmp, typeof(*curr), task_list);
70
71 wake_up_state(curr->task, TASK_NORMAL);
72 list_del_init(&curr->task_list);
73
74 if (list_empty(&tmp))
75 break;
76
77 raw_spin_unlock_irq(&q->lock);
78 raw_spin_lock_irq(&q->lock);
79 }
80 raw_spin_unlock_irq(&q->lock);
81}
82EXPORT_SYMBOL(swake_up_all);
83
84void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
85{
86 wait->task = current;
87 if (list_empty(&wait->task_list))
88 list_add_tail(&wait->task_list, &q->task_list);
89}
90
91void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state)
92{
93 unsigned long flags;
94
95 raw_spin_lock_irqsave(&q->lock, flags);
96 __prepare_to_swait(q, wait);
97 set_current_state(state);
98 raw_spin_unlock_irqrestore(&q->lock, flags);
99}
100EXPORT_SYMBOL(prepare_to_swait_exclusive);
101
102long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
103{
104 unsigned long flags;
105 long ret = 0;
106
107 raw_spin_lock_irqsave(&q->lock, flags);
108 if (signal_pending_state(state, current)) {
109 /*
110 * See prepare_to_wait_event(). TL;DR, subsequent swake_up_one()
111 * must not see us.
112 */
113 list_del_init(&wait->task_list);
114 ret = -ERESTARTSYS;
115 } else {
116 __prepare_to_swait(q, wait);
117 set_current_state(state);
118 }
119 raw_spin_unlock_irqrestore(&q->lock, flags);
120
121 return ret;
122}
123EXPORT_SYMBOL(prepare_to_swait_event);
124
125void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
126{
127 __set_current_state(TASK_RUNNING);
128 if (!list_empty(&wait->task_list))
129 list_del_init(&wait->task_list);
130}
131
132void finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
133{
134 unsigned long flags;
135
136 __set_current_state(TASK_RUNNING);
137
138 if (!list_empty_careful(&wait->task_list)) {
139 raw_spin_lock_irqsave(&q->lock, flags);
140 list_del_init(&wait->task_list);
141 raw_spin_unlock_irqrestore(&q->lock, flags);
142 }
143}
144EXPORT_SYMBOL(finish_swait);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * <linux/swait.h> (simple wait queues ) implementation:
4 */
5
6void __init_swait_queue_head(struct swait_queue_head *q, const char *name,
7 struct lock_class_key *key)
8{
9 raw_spin_lock_init(&q->lock);
10 lockdep_set_class_and_name(&q->lock, key, name);
11 INIT_LIST_HEAD(&q->task_list);
12}
13EXPORT_SYMBOL(__init_swait_queue_head);
14
15/*
16 * The thing about the wake_up_state() return value; I think we can ignore it.
17 *
18 * If for some reason it would return 0, that means the previously waiting
19 * task is already running, so it will observe condition true (or has already).
20 */
21void swake_up_locked(struct swait_queue_head *q, int wake_flags)
22{
23 struct swait_queue *curr;
24
25 if (list_empty(&q->task_list))
26 return;
27
28 curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
29 try_to_wake_up(curr->task, TASK_NORMAL, wake_flags);
30 list_del_init(&curr->task_list);
31}
32EXPORT_SYMBOL(swake_up_locked);
33
34/*
35 * Wake up all waiters. This is an interface which is solely exposed for
36 * completions and not for general usage.
37 *
38 * It is intentionally different from swake_up_all() to allow usage from
39 * hard interrupt context and interrupt disabled regions.
40 */
41void swake_up_all_locked(struct swait_queue_head *q)
42{
43 while (!list_empty(&q->task_list))
44 swake_up_locked(q, 0);
45}
46
47void swake_up_one(struct swait_queue_head *q)
48{
49 unsigned long flags;
50
51 raw_spin_lock_irqsave(&q->lock, flags);
52 swake_up_locked(q, 0);
53 raw_spin_unlock_irqrestore(&q->lock, flags);
54}
55EXPORT_SYMBOL(swake_up_one);
56
57/*
58 * Does not allow usage from IRQ disabled, since we must be able to
59 * release IRQs to guarantee bounded hold time.
60 */
61void swake_up_all(struct swait_queue_head *q)
62{
63 struct swait_queue *curr;
64 LIST_HEAD(tmp);
65
66 raw_spin_lock_irq(&q->lock);
67 list_splice_init(&q->task_list, &tmp);
68 while (!list_empty(&tmp)) {
69 curr = list_first_entry(&tmp, typeof(*curr), task_list);
70
71 wake_up_state(curr->task, TASK_NORMAL);
72 list_del_init(&curr->task_list);
73
74 if (list_empty(&tmp))
75 break;
76
77 raw_spin_unlock_irq(&q->lock);
78 raw_spin_lock_irq(&q->lock);
79 }
80 raw_spin_unlock_irq(&q->lock);
81}
82EXPORT_SYMBOL(swake_up_all);
83
84void __prepare_to_swait(struct swait_queue_head *q, struct swait_queue *wait)
85{
86 wait->task = current;
87 if (list_empty(&wait->task_list))
88 list_add_tail(&wait->task_list, &q->task_list);
89}
90
91void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state)
92{
93 unsigned long flags;
94
95 raw_spin_lock_irqsave(&q->lock, flags);
96 __prepare_to_swait(q, wait);
97 set_current_state(state);
98 raw_spin_unlock_irqrestore(&q->lock, flags);
99}
100EXPORT_SYMBOL(prepare_to_swait_exclusive);
101
102long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state)
103{
104 unsigned long flags;
105 long ret = 0;
106
107 raw_spin_lock_irqsave(&q->lock, flags);
108 if (signal_pending_state(state, current)) {
109 /*
110 * See prepare_to_wait_event(). TL;DR, subsequent swake_up_one()
111 * must not see us.
112 */
113 list_del_init(&wait->task_list);
114 ret = -ERESTARTSYS;
115 } else {
116 __prepare_to_swait(q, wait);
117 set_current_state(state);
118 }
119 raw_spin_unlock_irqrestore(&q->lock, flags);
120
121 return ret;
122}
123EXPORT_SYMBOL(prepare_to_swait_event);
124
125void __finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
126{
127 __set_current_state(TASK_RUNNING);
128 if (!list_empty(&wait->task_list))
129 list_del_init(&wait->task_list);
130}
131
132void finish_swait(struct swait_queue_head *q, struct swait_queue *wait)
133{
134 unsigned long flags;
135
136 __set_current_state(TASK_RUNNING);
137
138 if (!list_empty_careful(&wait->task_list)) {
139 raw_spin_lock_irqsave(&q->lock, flags);
140 list_del_init(&wait->task_list);
141 raw_spin_unlock_irqrestore(&q->lock, flags);
142 }
143}
144EXPORT_SYMBOL(finish_swait);